The government and the auto industry are promoting electric transportation as a way to cut U.S. dependence on foreign oil, ease the need for more U.S. oil drilling and cut carbon dioxide in the air. But the technology remains a colossal gamble, with billions invested by the industry and billions in subsidies from the government for research, factories and a direct-to-consumer rebate of $7,500 to partially offset the higher price of electrics.

Buyers still have to be convinced that being Earth-friendly is worth several trade-offs — beyond the cars' sticker prices, which can be double the cost of a similarly sized conventional car. Most prominently, most electric cars for now will have a range of about 100 miles before they need to be recharged. That process can take as few as 30 minutes with special chargers, but in most situations will take up to eight hours.

Even if you haven't paid attention to electric cars, you soon won't be able to escape hearing about them. Nissan has started its ad campaign for the fully electric Leaf. Chevrolet is about to crank up promotion for the Volt, a plug-in electric that also has an onboard generator powered by an auxiliary gas engine. Electric advocacy groups, such as Plug In America, plan their own public education campaigns.